The present invention generally relates to mobile communications systems and more particularly to a system and method for a handoff in an Internet Protocol (IP) based multimedia mobile network.
In a mobile communications system such as an IP based multimedia mobile network, it is critical that continuity and quality of service be maintained when a mobile end user moves between coverage areas associated with system access points. This is particularly true in the case of real-time applications such as VoIP, video over IP, teleconferencing, and instant messaging. It is generally recognized that connection latency between mobile devices cannot exceed 50 milliseconds. Current techniques for switching between one access point and another require hundreds of milliseconds.
Prior art systems and methods for providing handoff management include a system utilizing the concept of an anchor as disclosed in U.S. Pat. No. 6,160,804 entitled “Mobility Management for a Multimedia Mobile Network”. An anchor is a network node that is assigned to a mobile user station and acts as a permanent node, until deleted or changed, to which packets may be intermediately sent. The anchor then passes the packets on to the mobile station, regardless of where the mobile station has moved to in the system. Thus packets are directed to an anchor which then directs the packets to the mobile station. If a mobile station moves a sufficient distance from its anchor, the system makes a decision to change the anchor of the mobile station to be a closer network node so as to optimize packet routing.
Another handoff management system is disclosed in U.S. Pat. No. 6,735,202 entitled “Mobility Management Techniques for Use in an Internet Protocol-Based Multimedia Mobile Network”. Each network node is equipped with a handoff module that is responsible for collecting relevant information from neighboring nodes. Mobiles communicating with the network node also assist in handoff decisions by providing signal strength information from neighboring nodes. Based on the information at its disposal, the handoff manager makes the decisions as to when and to which node a mobile should handoff.
While the systems and methods of the prior art provide for handoff management, there continues to be a need for a system and method for a handoff in an IP-based multimedia mobile network which further reduces connection latency. The system and method include creating a plurality of virtual association clients in a mobile device. The virtual association clients establish associations between the mobile device and a plurality of access points without establishing a connection between the mobile device and the associated access points.